The quick couplings already known are those components used to reactivate or cut off connection between two branches of a fluid circuit without the need for any further operation.

Quick couplings generally consist of two half couplings or unions in each of which a check valve is mounted.

A mushroom valve is placed in each half of the coupling.

During normal running the two valves are open and together they auto- matically become balanced.

When the two unions are separated, the valves automatically close due to thrust exercised by springs so that, during the operation, losses are reduced to a minimum and penetration of particles is prevented.

When the two unions are joined, if there is no difference between levels of pressure in the two isolated branches, or if any difference can be made up by compression from a spring, both valves open and continuity is

immediately established.

A problem frequently encountered is a difficulty over coupling and un- coupling due to the presence of residual pressure in the device.

For this reason high loads have to be used at the start to overcome residual pressure.

Purpose of this invention is to assist coupling and uncoupling by elminating residual pressure in the female half coupling and returning it by means of control pressure to its idle position when uncoupled and before coupling, as will be explained below.

Subject of the invention is a quick coupling for assisted connection of the male and female half couplings between two branches of a fluid circuit.

The female half coupling consists of a"female half-coupling group"com- prising a base containing a first housing for the female half coupling and a second housing for a servo control device for said female half coupling in order to zero residual pressure and let in control pressure.

The valve block of this female half coupling is formed of a cylindrical body with an upper head and a lower head projecting downward from a supporting liner and having a lower cylindrical extension.

Said base is fixed to a distributor comprising a delivery tube for main pressure, a discharge channel for residual pressure and a channel for pressure from the servo control.

Said servo control comprises a tubular piston worked by a push button, freely sliding inside a second housing communicating axially with the distributor's discharge channel.

About halfway along its length said piston has a narrower cylindrial area that creates a first chamber round the piston, connected to a first transversal channel that, after a 90° bend, extends down to the lower end of the base and joins up with the distributor's channel for servo control pressure.

Lower down on said tubular piston a further narrower cylindrical area creates a second chamber round said piston, through which chamber passes a hole opposite a second transversal channel leading into the liner housing in the lower end of the valve body head.

In this way, through the axial hole in the tubular piston, said housing communicates with the servo control housing and with the distributor's discharge channel.

Below said second transversal channel is a third transversal channel substantially parallel to the second one, this too leading into the housing of the liner at the position of the cylindrical extension to the valve body head.

Therefore, by pressing the piston down to an initial position, so causing the second chamber to coincide not only with the second channel but also with the third transversal channel, residual pressure in the female half coupling is eliminated through said channels, after said female half coupling has been detached from the male half coupling.

Then, by pressing the piston to a second end-stroke position, the second chamber becomes detached from the second channel maintaining connection with the third channel, and therefore continuity for discharge of residual pressure in the distributor's discharge channel while, simul- taneously, the first chamber is connected to the second channel, though maintaining connection with the first channel, communicating with the distributor's channel for servo control pressure.

All this, together with simultaneous discharge of residual pressure from the valve body liner, thrusts said valve body outwards to reach the position in which the locking balls, passing inside the housing made in the edges of the liner that houses the valve body, make possible engagement of the male coupling.

Lower down on the push botton for the piston is an extension of greater diameter, sliding in a first axial chamber that houses the piston.

Two coaxial compression springs, placed round the piston, determine its two positions.

The first internal spring makes contact between the bottom of a second cylindrical chamber, created round the piston immediately below the first chamber, and the lower extension to the push button.

The second external spring makes contact between the bottom of said second cylindrical chamber and said chamber's top where the first

chamber begins, projecting inwards to an extent approximately corres- ponding to the central point of the upper turn of said spring, whose inner central point then corresponds to the lower extension of the push button.

The piston's first position is therefore reached by compressing the first spring until said lower extension of the push button reaches the second external spring.

The piston's second position is reached when the second spring is also compressed to the end of the piston's stroke.

The valve body is pressed against the bottom of the housing in the base by a helical compression spring placed round the central tubular body of said valve body, making contact between a raised ring placed close to the upper head of the valve body and the lower head of the valve body projecting from its central tubular body.

Seal packing is placed on the lower head of the valve body at the edge of the liner and on the bottom of the housing at the position of the cylindrical extension of the lower head between the second and third transversal channels, the purpose of said packing being to ensure separation of the discharge flow of residual pressure from the flow of control pressure.

Disengagement of the male half coupling is done in the same way as for engagement, using the servo control push button to move the piston into its first position for discharge of residual pressure through the second and third transversal channels, then moving the piston into a second position to continue said discharge through the third channel and, through the second channel, to let in control pressure supplied through the first channel and through the distributor's pressure control channel.

The invention offers evident advantages.

Couplings can be easily engaged and disengaged even if residual pressure is still present in the system.

Loads needed for coupling are reduced as these are no longer deter- mined by values of residual pressure.

Although the effects it produces are so important, the device is compact, easy to maintain and extremely simple to use.

Coupling and uncoupling are made easy obtaining maximum effects with

minimum effort, reducing stress for operators and wear on materials.

Characteristics and purposes of the invention will be made still clearer by the following example of its execution illustrated by diagrammatically drawn figures.

Fig. 1 Quick coupling with male half coupling and female half-coupling group, subject of the invention, before coupling, a longitudinal section.

Fig. 2 As above, during elimination of residual pressure in the female half coupling, a longitudinal section.

Fig. 3 As above, when servo control pressure is being put into the female half-coupling group, with movement of the valve body to engage the male half coupling, a longitudinal section.

The quick coupling 10, for the two branches of a fluid circuit, comprise the male half coupling 11, of a type already known, with an annular channel 15 for the ball locking device 43, and a female half-coupling group fixed to a distributor 100.

The distributor 100 comprises a delivery channel 101, and discharge channels 102 and 103 for pressure supplied by servo control.

The female half-coupling group 20 comprises a base 60 with housings 61 and 62 respectively for the female half coupling 21 and for servo control 80 for said female half coupling 21.

The female half coupling 21 comprises a cylindrical liner 22, to house the valve body 40, fixed in said housing 61 in the base 60 by lower threading 23.

Close to the edge of the liner 22, is an annular channel 25, of a semi- circular transversal section, for housing balls 43 placed inside holes 24 close to the edge of the valve body 40 to lock the male half coupling 11.

On the valve body 40 is an upper head 41 connected by a cylindrical body 42 to a lower head 44 with a downward cylindrical extension 45.

The valve 50 is lodged in the inner chamber 46 of said valve body 40.

Said chamber 46 communicates, through branches 51 and 52, with the channel 53 in line with the delivery channel 101 of the distributor 100.

Below the head 41, said liner 22 presents a raised inner ring 27.

A helical compression spring 26 is placed between the lower side of said

ring 27 and the upper head 44 of the valve body 40.

The servo control 80 for the female half coupling 21, comprises a tubular piston 82 open internally, fixed to a push button 81 that slides freely inside the cylindrical housing 62 of the base 60, aligned and communi- cating with the channel 102 of the distributor 100 fixed to the push button 81.

Close to the push button 81 said housing 62 presents, in sequence: a cylindrical chamber 66 in which the annular extension 83 of the push button 81 slides; an axial cylindrical chamber 67 of a larger diameter, and a cylindrical hole 68, of a diameter corresponding to that of the piston 82, which extends to the lower end of the base 60 connecting with the discharge channel 102 of the distributor 100.

At the position of chambers 66 and 67, in said piston 82 there is a cyiin- drical cavity 84 of a smaller diameter, which contributes to formation of said chambers 66 and 67.

A short distance from said cavity 84 of a smaller diameter, is a zone of equal diameter that forms a first cylindrical chamber 85, communicating with a first channel 70 formed by two branches at 90°, and connecting up with the channel 103 of the distributor 100 for control pressure.

On said piston 82, at a short distance from said first chamber 85, is a second chamber 86 of the same diameter.

At the position of said chamber 86, holes 87 pass through the piston 82, said holes being aligned with a second transversal channel 71 which, passing through the base 60, leads into the bottom of the housing 61 at the lower end of the lower head of the valve body 40, projecting from the lower edge of the liner 22, immediately below seal packing 95 placed round said lower head.

Below this, and substantially parallel to said channel 71, is a third channel 72 that, passing through the base 60, leads into the bottom of said housing 61 at the position of the lower cylindrical extension 45 to said lower head 44.

Seal packing 47 is placed between said second channel 71 and the third transversal channel 72.

Placed coaxially round the piston 82 are two helical compressiion springs 90 and 91.

The internal spring 90 makes contact uppermost against the lower end of the push button 81 and contact below against the edge of the chamber 67 that surrounds the piston 82.

With the external centre of its upper turn, the external spring 91 makes contact uppermost against the top of said chamber 67 and contact below against the bottom of said chamber.

To engage the male half coupling 11 with the female half coupling 21 proceed as follows.

A finger is used to press the push button 81 (Fig. 2) of the servo control 80 for the female half-coupling group 20 until the internal spring 90 is compressed and contact made between the tubular extension 83 and the external spring 91.

In this position the chamber 86 of the piston 82 lies opposite the two transversal channels 71 and 72 causing residual pressure, in the bottom of housing 61 for the female half coupling, to zero through the hole 88 in the piston 82 that communicates with the discharge channel 102 of the distributor 100.

By maintaining pressure on the push button 81 of the servo control 80, causing compression of both springs 90 and 91 to the end of the stroke (Fig. 3), the first chamber 85 of the piston 82 matches both with the second channel 71 and with the first channel 70 connected to channel 103 of the distributor 100, while the third channel 72 still communicates with the chamber 86 of said piston 82.

Through distributor 100, control pressure is therefore created against the lower head 44 of the valve body 40, while the bottom of housing 62 remains in communication with the discharge channel 102.

The effect of all this is to move said valve body 40 towards the outside of the liner 22 its position then being such that the balls 43 can move to the internal half ring 25 of said liner 22 allowing passage of the male half coupling 11 and so engaging it, through said balls, with the female half coupling 21.

To disengage the male half coupling 11, the process is substantially that already described.

When the push button 81 is pressed down to the end of its stroke, the springs on the valves of the male half coupling 11 and of the female half coupling 21, automatically expel the male half coupling 11.

This having been done, the push button for the servo control 80 of the female half-coupling group is released.